A. Field of the Invention
The present invention relates to a means and method for dimming ballasted lamps, and in particular, relates to a means and method for changing light output from a lamp or lamps by adjusting the ballast for a lamp or an array of lamps.
B. Problems in the Art
Many types of lamps, particularly those used for wide scale and high intensity lighting, utilize ballasts for providing sufficient starting power to the lamps and at the same time preventing current run-away through the lamp. They are also beneficial to maintain the stability for a lamp or an array of lamps.
It is therefore necessary to match the specification of the ballast to the particular lamp or array of lamps to allow the ballast to achieve its particular functions. The lamp or array of lamps can thus be controlled to turn on efficiently, and operate in an efficient and stable manner.
There are numerous times, however, when it would be desirable or beneficial to be able to achieve different light levels out of one lamp or an array of lamps. For example, for wide area, high powered arrays of lamps utilized to light tennis courts, it can be desirable to have easy and efficient starting and operation of those lights. It can then be desirable to dim those lights for those tennis courts when they are not being used. It might also be desirable to be able to use some lights at full intensity, but have other lights which are not directly needed for use to be dimmed (such as those on unused courts). Those lights would then serve to provide low level illumination for persons walking to or past those tennis courts and be quickly available to be operated at full intensity when those particular courts are to be used.
Because lamps of these types often take considerable time to start, it can be beneficial to have the lights in at least the dimmed condition so that they can be quickly brought to full light output, rather than started cold, or restarted. It is to be understood that to allow dimming would realize a savings in energy, over and against operating the lamps at full power all the time. It may also contribute to longer lamp-life, depending on what type and power of lamp is used.
It is to be further understood that other examples of the need for such lighting are numerous, including but not limited to, other types of sports lighting (both indoor and outdoor), intermittent special events lighting, timed period lighting, and the like. It would be advantageous to be able to adjust the lighting between full intensity and dimmed intensity. It may also be advantageous to be able to adjust the lights between a plurality of different lighting levels. Thus, one set of wide area, high intensity lamps could be used for different purposes.
Some attempts have been made to allow for dimming of ballasted lamps. Many of these methods are either complex or expensive, or result in instability of the lighting when switched to the dimmer intensity. Instability can cause flutter or color change in the light, both of which are generally undesirable.
Another problem with some of these methods is that they require a dimming system for each lamp. This is not only costly, but necessarily involves the operation of dimming means on an individual fixture basis, rather than on the more efficient and controllable multi-lamp method.
It would simply be too uneconomical to have lighting fixtures which contain different powered lamps for different light outputs. Presently attempted methods are not completely successful in solving the above mentioned problems. It is to be understood that present methods also have the problem of many times being able to dim the lamps effectively by changing the input voltage of the ballast for each lamp, but this can result in having insufficient voltage to start the lamp or lamps, particularly in cold weather conditions.
There is no current economical, efficient, and reliable multilevel light output means or method for ballasted lamps. There is therefore a real need in the art for such an improvement.
There are also certain needs whereby it would be advantageous to have automatic dimming of lighting, when full intensity lighting is not needed. This could be advantageous for indoor sports lighting, such as gymnasiums, where a certain level of lighting intensity below full intensity could be utilized when the playing field or court is not in use. It could also be applied to lighting whereby if full intensity lighting is used for a period of time, the lighting would automatically dim unless instructed otherwise. This would save energy and could save bulb life. Such a system could also be used to notify a spectator audience of the end or beginning of events; such as different periods of an athletic contest, or different races at a horse racing track, etc.
It is therefore the principle object of the present invention to provide a means and method for dimming ballasted lamps which improves over or solves the problems and deficiencies in the art.
Another object of the present invention is to provide a means and method as above described which allows constant and adequate electrical power for starting ballasted lamps, while at the same time allowing for selection between full lighting intensity and one or more dimmed levels.
A further object of the present invention is to provide a means and method as above described which insures sufficient starting power, even when the lamp or lamps are switched to a dimmed level.
A still further object of the present invention is to provide a means and method as above described which does not produce unacceptable instability or color change in the output of the lamps.
Another object of the present invention is to provide a means and method as above described which can provide dimming for one lamp, a plurality of lamps, or a plurality of arrays of lamps.
A further object of the present invention is to provide a means and method as above described which can easily be incorporated into newly constructed lighting fixtures or arrays, or which can be easily retrofitted to existing lighting fixtures or arrays, and which can be used for either indoor or outdoor lighting applications.
Another object of the present invention is to provide a means and method as above described which can, in certain situations, beneficially effect and prolong lamp life.
Another object of the present invention is to provide a means and method as above described which can assist in savings of energy and power consumption.
A further object of the present invention is to provide a means and method as above described which is economical to manufacture, assemble, maintain, and service.
Another object of the present invention is to provide a means and method as above described which is efficient, reliable, and durable.
These and other objects, features, and advantages of the invention will become more apparent with reference to the accompanying specifications and claims.